Theoretical analysis of the thermodynamics of ZSM-11 zeolite synthesis

Journal Article · Thu Mar 20 04:00:00 EST 1997 · Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical

DOI:https://doi.org/10.1021/jp9631341· OSTI ID:501928

Shen, V; Watanabe, K; Bell, A T ^[1]

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1. Lawrence Berkeley National Lab., CA (United States)

Theoretical methods are used to analyze the thermodynamics of ZSM-11 synthesis from amorphous silica and an aqueous solution of tetraalkylammonium hydroxide (TAAOH). The overall process is represented by the reaction 96SiO{sub 2}(a){sup +} n(TAA{sup +}/OH{sup -}/200H{sub 2}O){sup =} (nTAA{sup +}/Z{sup n-}){sup +} 200nH{sub 2}O. Both tetrapropylammonium (TPA{sup +}) and tetrabutylammonium (TBA{sup +}) cations are considered as the structure-directing agents, and calculations are performed for occlusion of either three or four TAA{sup +} cations per unit cell of the zeolite. Both estimates of the change in internal energy and Gibbs free energy reveal that the synthesis of ZSM-11 should be favored by the occlusion of three TBA{sup +} cations per unit cell, consistent with experimental observation. The present analysis also demonstrates the importance of energy and entropy changes associated with the dehydration of TAA{sup +} and OH{sup -} ion and with the occlusion of TAA{sup +} cations into the zeolite. The interactions of OH{sup -} anions with the zeolite framework to form defects in the form of siloxy (=V@SiO{sup -}) groups are also considered. 46 refs., 5 tabs.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 501928
• Journal Information: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 12 Vol. 101; ISSN 1089-5647; ISSN JPCBFK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
99 GENERAL AND MISCELLANEOUS
AMMONIUM COMPOUNDS
ANIONS
AQUEOUS SOLUTIONS
CHEMICAL REACTIONS
FREE ENERGY
HYDROXIDES
MATHEMATICAL MODELS
MOLECULAR MODELS
SYNTHESIS
THEORETICAL DATA
THERMODYNAMICS
ZEOLITES